Microchip 'could do away with pills': BBC

[Ivan Seeking]

Scientists in the United States have developed a new way of taking medicines which could improve the effectiveness of some treatments including HIV therapy

http://news.bbc.co.uk/2/hi/health/3205800.stm

[hypnagogue]

Anyone have any idea how these 'chips' can work for up to 140 days? Why aren't they excreted after a day or two?